Lighting system

ABSTRACT

It is an object of the present invention to provide a lighting system having favorable luminance uniformity in a light-emitting region when the lighting system has large area. According to one feature of the invention, a lighting system comprises a first electrode, a second electrode, a layer containing a light-emitting substance formed between the first electrode and the second electrode, an insulating layer which is formed over a substrate in a grid form and contains a fluorescence substance, and a wiring formed over the insulating layer. The insulating layer and the wiring are covered with the first electrode so that the first electrode and the wiring are in contact with each other.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/575,984, filed Oct. 8, 2009, now allowed, U.S. Pat. No. 8,847,479which is a continuation of U.S. application Ser. No. 11/139,673, filedMay 31, 2005, now U.S. Pat. No. 7,733,441, which claims the benefit of aforeign priority application filed in Japan as Serial No. 2004-166041 onJun. 3, 2004, all of which are incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a lighting system using a light-emittingelement.

2. Description of the Related Art

A light-emitting element is a self light-emitting element and isattempted to be used as a lighting system. The light-emitting element isa surface-emitting body light, and a lighting system capable of emittingnear-natural light can be obtained by using the light-emitting elementfor lighting.

The light-emitting element has a layer containing a light-emittingsubstance which provides luminescence (Electroluminescence) by applyingan electric field thereto, an anode, and a cathode. A hole injected fromthe anode is combined with an electron injected from the cathode in thelayer containing a light-emitting substance, thereby obtainingluminescence. Luminescence obtained from the layer containing alight-emitting substance includes luminescence (fluorescence) that isobtained in returning from a singlet-excited state to a ground state andluminescence (phosphorescence) that is obtained in returning from atriplet-excited state to a ground state.

In a light-emitting device using such a light-emitting element, anelectrode in the direction of light emission needs to be transparent.However, a transparent conductive film which is typically used as atransparent electrode often has relatively high resistivity, and voltagedrop is caused in a portion away from a current supply terminal. Inparticular, the lighting system often made to emit light from the entiresurface at the same luminance; therefore, in-plane nonuniformity ofluminance becomes further noticeable.

However, when the lighting system has large area, luminance is loweredin a portion through which current is hard to flow. In other words,luminance is nonuniform in a light-emitting region of the lightingsystem. In addition, an ITO electrode typically used as the anode hashigher electrical resistivity than that of metal such as Al used as thecathode. Therefore, voltage drop is caused in a portion away from acurrent supply terminal, which results in low luminance. In order tosolve the problem, Reference 1 reports a structure in which at least aportion of an anode is provided with an auxiliary electrode having lowerelectrical resistivity than that of the anode (see Reference 1: JapanesePatent Laid Open No. 2004-134282).

In Reference 1, an auxiliary electrode is provided on a long side or ashort side of a light-emitting element. However, when the lightingsystem has large area, luminance is lowered in a part away from theauxiliary electrode (for example, in a central portion of the lightingsystem). However, since light emitted from a light-emitting layer cannotbe extracted outside when the auxiliary electrode is entirely providedover the anode in the structure of Reference 1, the auxiliary electrodecan only be partially provided.

Since the lighting system is often made to emit light from the entiresurface at the same luminance, nonuniformity of the luminance becomesfurther noticeable.

SUMMARY OF THE INVENTION

In view of the above problem, it is an object of the invention toprovide a lighting system having favorable luminance uniformity in alight-emitting region when the lighting system has large area.

According to one feature of a lighting system of the invention, a layercontaining a light-emitting substance is formed between a firstelectrode and a second electrode, and a third electrode is formed toconnect to the first electrode through an opening formed in the secondelectrode and the layer containing a light-emitting substance.

In other words, the lighting system has a layer containing alight-emitting substance and a second electrode between a firstelectrode and an auxiliary electrode; the auxiliary electrode is formedopposite to the first electrode with the second electrode therebetween;and the first electrode is electrically connected to the auxiliaryelectrode through an opening formed in the second electrode and thelayer containing a light-emitting substance. Note that the firstelectrode and the second electrode need to be electrically insulatedfrom the second electrode and the auxiliary electrode, respectively.

More specifically, according to another feature of the invention, alayer containing a light-emitting substance provided with a firstopening and a second electrode provided with a second opening arearranged over a first electrode formed of a transparent conductive filmso that the second opening overlaps the first opening; and an insulatinglayer formed over the second electrode, covering the first opening, thesecond opening, and the side of the second opening, and provided with athird opening to expose the first electrode and a third electrode formedover the insulating layer to be in contact with the first electrodethrough the first to third openings are formed.

According to another feature of the invention, a plurality of openingsis formed in a light-emitting region of a lighting system.

In the above structure, light emitted from the layer containing alight-emitting substance is emitted from the first electrode side. Inother words, the first electrode transmits light and is formed of atransparent conductive film. Specifically, indium tin oxide (hereinafterreferred to as ITO), indium tin oxide containing silicon, indium oxidecontaining zinc oxide (ZnO) of 2% to 20%, or the like can be used.

Note that a material having low resistivity is preferably used as theauxiliary electrode. An effect of voltage drop due to relatively highresistivity of the first electrode can be reduced by using a materialhaving low resistivity.

In the above structure, the layer containing a light-emitting substancemay have a stacked structure of a plurality of layers each including alight-emitting substance.

Further in the above structure, a substrate for supporting the lightingsystem may be a flexible substrate.

In the above structure, no light is lost except in a connection portionof the auxiliary electrode and the first electrode because the auxiliaryelectrode is not placed in the direction of light emission. Therefore, amaterial, a thickness, or a formation position of the auxiliaryelectrode can be arbitrarily set.

In the case where the area of the connection portion of the auxiliaryelectrode and the first electrode is sufficiently small, the presence ofthe auxiliary electrode can be substantially disregarded even when seenfrom the side of light emission. Therefore, a plurality of openings canbe formed in a light emitting region of the lighting system.

According to another feature of the invention, a lighting systemcomprises a first electrode, a second electrode, a layer containing alight-emitting substance formed between the first electrode and thesecond electrode, an insulating layer which is formed over a substratein a grid form and contains a fluorescence substance, and a wiringformed over the insulating layer, in which the insulating layer and thewiring are covered with the first electrode so that the first electrodeand the wiring are in contact with each other.

According to the invention, a lighting system having preferable in-planeuniformity of luminance can be obtained. Since an auxiliary electrode isnot placed in the direction of light emission, little light is lost dueto the auxiliary electrode, and a material, a thickness, or a formationposition of the auxiliary electrode can be arbitrarily set.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are each a cross-sectional view and a top view of alight-emitting region in a lighting system according to a certain aspectof the present invention;

FIGS. 2A to 2D each illustrate a method for manufacturing a lightingsystem according to a certain aspect of the present invention;

FIGS. 3A to 3C each illustrate a method for manufacturing a lightingsystem according to a certain aspect of the present invention;

FIGS. 4A to 4C each illustrate a method for manufacturing a lightingsystem according to a certain aspect of the present invention;

FIGS. 5A and 5B are each a cross-sectional view and a top view of alight-emitting region in a lighting system according to a certain aspectof the present invention;

FIGS. 6A to 6C each illustrate a method for manufacturing a lightingsystem according to a certain aspect of the present invention;

FIGS. 7A and 7B each illustrate a method for manufacturing a lightingsystem according to a certain aspect of the present invention;

FIGS. 8A and 8B are each a top view and a cross-sectional view of alighting system according to a certain aspect of the present invention;

FIG. 9 illustrates an example of a device using a lighting systemaccording to a certain aspect of the present invention;

FIGS. 10A to 10C each illustrate an example of a device using a lightingsystem according to a certain aspect of the present invention;

FIG. 11 illustrates an example of a layer containing a light-emittingsubstance of a lighting system according to a certain aspect of thepresent invention;

FIG. 12 illustrates an example of a layer containing a light-emittingsubstance of a lighting system according to a certain aspect of thepresent invention;

FIGS. 13A and 13B each explain a mode of a lighting system according toa certain aspect of the present invention;

FIGS. 14A to 14C each explain a method for manufacturing a lightingsystem according to a certain aspect of the present invention;

FIGS. 15A to 15C each explain a method for manufacturing a lightingsystem according to a certain aspect of the present invention; and

FIGS. 16A and 16B each explain a mode of a lighting system according toa certain aspect of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiment Mode of the present invention will be described in detailwith reference to the accompanying drawings. However, the invention isnot limited to the following description. As is easily known to a personskilled in the art, the mode and the detail of the invention can bevariously changed without departing from the purpose and the scope ofthe invention. Thus, the invention is not interpreted while limiting tothe following description of the embodiment modes.

Embodiment Mode 1

A structure of a lighting system according to the present invention isdescribed with reference to FIGS. 1A and 1B. The lighting systemillustrated in FIGS. 1A and 1B is a bottom emission lighting systemwhich emits light from a substrate side. Note that FIG. 1B is a top viewof a light-emitting region in a lighting system of the invention andFIG. 1A is a cross-sectional view (taken along line A-A′ in FIG. 1B) invicinity of an opening in the light-emitting region.

In FIGS. 1A and 1B, a light-transmitting substrate is used as asubstrate 101. Specifically, a light-transmitting material such asglass, plastic, polyester, or an acryl resin can be used. The substrate101 may be flexible.

A transparent conductive film is formed over the substrate 101 as afirst electrode 102. For example, indium tin oxide (hereinafter referredto as ITO), indium tin oxide containing silicon, indium oxide containingzinc oxide (ZnO) of 2% to 20%, or the like can be used for thetransparent conductive film.

A layer containing a light-emitting substance 103 is formed over thefirst electrode 102. The layer containing a light-emitting substance 103can be formed using a known material, and either a low molecular weightmaterial or a high molecular weight material can also be used. Amaterial to form the layer containing a light-emitting substance mayinclude not only the one formed of only an organic compound material butalso the one partially containing an inorganic compound. The layercontaining a light-emitting substance is formed by appropriatelycombining a hole injecting layer, a hole transporting layer, a holeblocking layer, a light-emitting layer, an electron transporting layer,an electron injecting layer, or the like. The layer containing alight-emitting substance may be a single layer or have a stuckedstructure of a plurality of layers. FIG. 11 illustrates an example of astructure in which the layer containing a light-emitting substanceincludes a hole injecting layer, a hole transporting layer, alight-emitting layer, an electron transporting layer, and an electroninjecting layer. In FIG. 11, a first electrode (anode) 1101, a layercontaining a light-emitting substance 1102, and a second electrode(cathode) 1103 are formed over a substrate 1100. The layer containing alight-emitting substance 1102 includes a hole injecting layer 1111, ahole transporting layer 1112, a light-emitting layer 1113, an electrontransporting layer 1114, and an electron injecting layer 1115. Note thatthe layer containing a light-emitting substance in a lighting system ofthe invention is not limited to the structure of FIG. 11. Hereinafterdescribes specific materials used for the hole injecting layer, the holetransporting layer, the light-emitting layer, the electron transportinglayer, and the electron injecting layer.

A porphyrin-based compound is effective among other organic to compoundsas a material having hole injectability for forming the hole injectinglayer, and phthalocyanine (hereinafter referred to as H₂-Pc), copperphthalocyanine (hereinafter referred to as Cu-Pc), or the like can beused. In addition, a chemically doped high molecular weight conductivecompound can be used, such as polyethylene dioxythiophene (hereinafterreferred to as PEDOT) doped with polystyrene sulfonate (hereinafterreferred to as PSS). A benzoxazole derivative and any one or more ofTCQn, FeCl₃, C₆₀, and F₄TCNQ may be included.

An aromatic amine based compound (in other words, an compound having abenzene ring-nitrogen bond) is preferably used as a material having holetransportability for forming the hole transporting layer. The followingcan be given as an example of materials that are widely used:N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine(hereinafter referred to as TPD), a derivative thereof such as4,4′-bis[N-(1-naphthyl)-N-phenyl-amino]-biphenyl (hereinafter referredto as α-NPD), or a star burst aromatic amine compound such as4,4′,4″-tris(N-carbazolyl)-triphenylamine (hereinafter referred to asTCTA), 4,4′,4″-tris(N,N-diphenyl-amino)-triphenylarnine (hereinafterreferred to as TDATA) or4,4′,4″-tris[N-(3-methylphenyl)-N-phenyl-amino]-triphenylamine (referredto as MTDATA).

Various fluorescent pigments are specifically effective as alight-emitting material for forming the light-emitting layer in additionto the following metal complex: tris(8-quinolinolato)aluminum(hereinafter referred to as Alq₃),tris(4-methyl-8-quinolinolato)aluminum (hereinafter referred to asAlmq₃), bis(10-hydroxybenzo[h]-quinolinato)beryllium (hereinafterreferred to as BeBq₂),bis(2-methyl-8-quinolinato)(4-phenylphenolato)aluminum (hereinafterreferred to as BAlq), bis[2-(2-hydroxyphenyl)-benzooxazolate]zinc(hereinafter referred to as Zn(BOX)₂)₂),bis[2-(2-hydroxyphenyl)-benzothiazolate]zinc (hereinafter referred to asZn(BTZ)₂), or the like.

In the case of forming the light-emitting layer in combination with aguest material, the following material can be used as the guestmaterial: quinacridon, diethyl quinacridon (hereinafter referred to asDEQD), dimethyl quinacridon (hereinafter referred to as DMQD), rubrene,perylene, coumarin, coumarin545T (hereinafter referred to as C545T),DPT, Co-6, PMDFB, BTX, ABTX, DCM, DCJT, or a triplet light-emittingmaterial (phosphorescence material) such astris(2-phenylpyridine)iridium (hereinafter referred to as Ir(ppy)₃), or2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin-platinum (hereinafterreferred to as PtOEP).

The following material can be used as a material having electrontransportability that can be used for the electron transportinglayer:2-(4-biphenylyl)-5-(4-tert-buthylphenyl)-1,3,4-oxadiazole(abbreviated to PBD),1,3-bis[5-(p-tert-buthylphenyl)-1,3,4-oxadiazole-2-yl]benzene(abbreviated to OXD-7),3-(4-tert-buthylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triazole(abbreviated to TAZ),3-(4-tert-buthylphenyl)-4-(4-ethylpheyl)-5-(4-biphenylyl)-1,2,4-triazole(abbreviated to p-EtTAZ), bathophenanthroline (abbreviated to BPhen),bathocuproin (abbreviated to BCP), or the like, in addition to theforegoing metal complex such as Alg₃, Almq₃,bis(2-methyl-8-quinolinato)(4-phenylphenolato)aluminum (abbreviated toBAlq), BeBq₂, Zn(BOX)₂, or Zn(BTZ)₂, or a metal complex such astris(8-quinolinolato)gallium (abbreviated to Gaq₃) orbis(2-methyl-8-quinolinato)-4-phenylphenolate-gallium (abbreviated toBGaq).

Specifically, an ultrathin film of an insulating material, for example,halogenated alkali metal such as LiF or CsF, halogenated alkali earthmetal such as CaF₂, alkali metal oxide such as Li₂O, or the like isoften used as a material having electron injectability for forming theelectron injecting layer. In addition, an alkali metal complex such aslithium acetylacetonate (abbreviated to Li(acac)) or8-quinolinato-lithium (abbreviated to Liq) is also effective. Abenzoxazole derivative and any one or more of alkali metal, alkali earthmetal, and transition metal may be included.

Note that the layer containing a light-emitting substance 103 may have astacked structure of a plurality of layers each containing alight-emitting substance. FIG. 12 illustrates an example of a stackedstructure of a plurality of layers each containing a light-emittingsubstance. FIG. 12 illustrates a structure in which a first electrode1201, a first layer containing a light-emitting substance 1202, a chargegenerating layer 1203, a second layer containing a light-emittingsubstance 1204, and a second electrode 1205 are stacked over a substrate1200. The charge generating layer 1203 needs to be formed of a highlylight-transmitting material having a function of injecting a carrier.Although FIG. 12 illustrates a stacked structure of the two layers eachcontaining a light-emitting substance, the structure of the layercontaining a light-emitting substance 103 is not limited thereto, and astacked structure of three or more layers each containing alight-emitting substance may be employed, too. In addition, the firstelectrode is used as the electrode on the substrate side in FIG. 12;however, the second electrode may be used as the electrode on thesubstrate side.

Luminance is enhanced by employing the stacked structure of layers eachcontaining a light-emitting substance. The more layers are stucked, themore the luminance can be enhanced even with the same amount of current.In particular, a stacked structure of layers each containing alight-emitting substance is suitable for lighting use which requireshigh luminance. In the case of forming the stacked structure of aplurality of layers each containing a light-emitting substance, thelayers each containing a light-emitting material may be formed of thesame material or different materials.

For example, when layers each containing a light-emitting substanceformed of materials which emit red (R), green (G), and blue (B) lightmay be stacked, white light emission can be obtained as a whole. Thematerials which emit red (R), green (G), and blue (B) light may each beformed by a vapor deposition method using a vapor-deposition mask, adroplet discharging method (also referred to as an ink-jet method), orthe like. Specifically, CuPc or PEDOT can be used as the hole injectinglayer; α-NPD, for the hole transporting layer; BCP or Alq₃, for theelectron transporting layer; and BCP: Li or CaF₂, for the electroninjecting layer, respectively. In addition, the light-emitting layer maybe formed using Alg₃ doped with dopant (DCM or the like in the case of Ror DMQD or the like in the case of G) corresponding to each lightemission of R, G, and B, for example. In the case of obtaining whitelight emission, not only the stacked structure of the light-emittingmaterials of three colors as mentioned above but also a stackedstructure of light-emitting materials of two colors may be employed. Forexample, white light emission can also be obtained by stacking thematerials which emit blue and yellow light.

Note that the structure of the layer containing a light-emittingsubstance is not limited to the above stacked structure. For example,the layer containing a light-emitting substance may be any one of asingle layer type, a stacked layer type, and a mixed type without aninterface between layers. In addition, a fluorescent material, aphosphorescent material, or a combined material thereof can be used. Forexample, a phosphorescent material can be used for the material whichemits red (R) light, and a fluorescent material can be used for thematerials which emit green (G) and blue (B) light. Further, any one ofthe following may be used: an organic material including a low molecularweight material, a high molecular weight material, and a middlemolecular weight material; an inorganic material typified by molybdenumoxide superior in terms of electron injectability and the like; and acomposite material of the organic material and the inorganic material.

The lighting system of the invention may be formed to provide not onlywhite light but also desired-color light. In addition, a color filterand/or a color conversion layer may be separately provided.

A second electrode 104 is formed over the layer containing alight-emitting substance 103. A known material can be used for thesecond electrode 104. In the case of a cathode, the second electrode 104is preferably formed using a conductive material having a low workfunction. Specifically, rare-earth metal such as Yb or Er in addition toalkali metal such as Li or Cs, alkali earth metal such as Mg, Ca, or Sr,or an alloy thereof (Mg: Ag, Al: Li, or the like) can be used to formthe cathode. When an electron injecting layer formed of LiF, CsF, CaF₂,Li₂O, or the like is used, a conductive thin film of aluminum or thelike can be used. In the case of an anode, the second electrode 104 ispreferably formed using a conductive material having a high workfunction. Specifically, a stacked layer structure of a titanium nitridefilm and a film mainly containing aluminum; a three-layer structure of atitanium nitride film, a film mainly containing aluminum, and a titaniumnitride film; or the like can be employed in addition to a single layerfilm of TiN, ZrN, Ti, W, Ni, Pt, Cr, or the like. Alternatively, amethod for stacking a transparent conductive film over a reflectiveelectrode of Ti, Al, or the like may also be employed.

An insulating film 105 is formed to cover the second electrode 104 andthe layer containing a light-emitting substance 103. According to thisinsulating film 105, the first electrode 102 and the second electrode104, and the second electrode 104 and an auxiliary electrode 106 areeach electrically insulated. The insulating film 105 may have a functionas a protective film for preventing transmission of a substance such asmoisture or oxygen to be the cause of promoting deterioration of thelayer containing a light-emitting substance.

The insulating film 105 partially has an opening 107, through which thefirst electrode 102 is electrically connected to the auxiliary electrode106. A material having low resistivity is preferably used for theauxiliary electrode 106; specifically, a material such as aluminum,copper, or silver can be used. In addition, the diameter of the openingis set from 10 μm to 500 μm, preferably from 50 μm to 200 μm.

In addition, a light-emitting region 108 is provided with a plurality ofthe openings 107. Since the auxiliary electrode 106 is electricallyconnected to the first electrode 102 through this opening 107, an effectof voltage drop due to relatively high resistivity of the transparentconductive film can be reduced. In other words, since the auxiliaryelectrode 106 is electrically connected to the first electrode 102through the plurality of openings 107 formed in the light-emittingregion 108, the resistivity of the first electrode 102 can be loweredpractically. This can reduce nonuniformity of luminance that a portionaway from a current supply terminal is dark. When the size of theopening is sufficiently small, the presence of the auxiliary electrodecan be substantially disregarded when the lighting system is seen fromthe side of light emission, in other words, from the side of thelight-transmitting substrate. Since the auxiliary electrode is notplaced in the direction of light emission, a material, a thickness, or aformation position of the auxiliary electrode can be arbitrarily set.Therefore, the auxiliary electrode can be formed selectively in aposition where voltage tends to drop, or can be entirely formed over thelight-emitting region of the lighting system.

Since the lighting system of the invention can reduce the nonuniformityof luminance due to voltage drop caused by the first electrode, alighting system having favorable in-plane uniformity of luminance can beobtained. Specifically, the lighting system is preferably applied to alarge-sized lighting system.

Embodiment Mode 2

A structure of a lighting system according to the present invention isdescribed with reference to FIGS. 5A and 5B. A lighting systemillustrated in FIGS. 5A and 5B is a top emission lighting system inwhich light is emitted from the opposite side of a substrate side. Notethat FIG. 5B is a top view of a light-emitting region of the lightingsystem and FIG. 5A is a cross-sectional view (taken along line A-A′ inFIG. 5B) in vicinity of an opening in the light-emitting region.

In FIGS. 5A and 5B, a thin substrate formed of a flexile material isused as a substrate 501. Specifically, a flexible substrate such as aplastic substrate, a polyester film, or an acrylic resin film can beused.

A second electrode 502 is formed over the substrate 501. A knownmaterial can be used for the second electrode 502. In the case of acathode, the second electrode 502 is preferably formed using aconductive material having a low work function. Specifically, rare-earthmetal such as Yb or Er in addition to alkali metal such as Li or Cs,alkali earth metal such as Mg, Ca, or Sr, or an alloy thereof (Mg:Ag,Al:Li, or the like) can be used. When the electron injecting layer ofLiF, CsF, CaF₂, Li₂O, or the like is used, a conductive thin film ofaluminum can be used. In the case of an anode, the second electrode 502is preferably formed using a conductive material having a high workfunction. Specifically, a stacked layer structure of a titanium nitridefilm and a film mainly containing aluminum; a three-layer structure of atitanium nitride film, a film mainly containing aluminum, and a titaniumnitride film; or the like can be employed in addition to a single layerfilm of TiN, ZrN, Ti, W, Ni, Pt, Cr, or the like. Alternatively, amethod for stacking a transparent conductive film over a reflectiveelectrode such as Ti or Al may also be employed.

A layer containing a light-emitting substance 503 is formed over thesecond electrode 502. The layer containing a light-emitting substance503 can be formed using a known material and either a low molecularweight material or a high molecular weight material can be used. Amaterial for forming the layer containing a light-emitting substanceincludes not only an organic compound material but also a materialpartially containing an inorganic compound. In addition, the layercontaining a light-emitting substance is formed by appropriatelycombining a hole injecting layer, a hole transporting layer, a holeblocking layer, a light-emitting layer, an electron transporting layer,an electron injecting layer, or the like; however, the layer containinga light-emitting substance may be formed in a single layer or may beformed by stacking a plurality of layers.

The layer containing a light-emitting substance 503 may have a stackedstructure of a plurality of layers each containing a light-emittingsubstance. Luminance is enhanced by employing the stacked structure oflayers each containing a light-emitting material. The more layers arestacked, the more the luminance can be enhanced even with the sameamount of current. In particular, the stacked structure of layers eachcontaining a light-emitting substance is suitable for lighting use whichrequires high luminance. In the case of forming the stacked structure ofa plurality of layers each containing a light-emitting substance, thelayers each containing a light-emitting substance may be formed of thesame material or different materials.

A transparent conductive film is formed over the layer containing alight-emitting substance 503 as a first electrode 504. For example,indium tin oxide (hereinafter referred to as ITO), indium tin oxidecontaining silicon, indium oxide containing zinc oxide (ZnO) of 2% to20%, or the like can be used for the transparent conductive film.

The substrate 501, the second electrode 502, the layer containing alight-emitting substance 503, and the first electrode 504 have anopening 507, and an insulating film 505 is formed to cover the vicinityof the opening of the first electrode 504 and the substrate 501 and thesidewall of the opening. According to this insulating film 505, thefirst electrode 504 and the second electrode 502, and the secondelectrode 502 and an auxiliary electrode 506 are each electricallyinsulated. The insulating film 505 may have a function as a protectivefilm for preventing transmission of a substance such as moisture oroxygen to be the cause of promoting deterioration of the layercontaining a light-emitting substance.

The auxiliary electrode 506 is formed over a lower surface of thesubstrate, in the opening, and in the vicinity of the opening of thefirst to electrode, and is electrically connected to the first electrodein the vicinity of the opening. A material having low resistivity ispreferably used for the auxiliary electrode 106; specifically, amaterial such as aluminum, copper, or silver can be used. In addition,the diameter of the opening is set from 10 μm to 500 μm, preferably from50 μm to 200 μm.

In addition, a light-emitting region 508 is provided with a plurality ofthe openings 507. Since the auxiliary electrode 506 is electricallyconnected to the first electrode 504 through the opening 507, an effectof voltage drop due to relatively high resistivity of the transparentconductive film can be reduced. In other words, since the auxiliaryelectrode 506 is electrically connected to the first electrode 504through the plurality of openings 507 formed in the light-emittingregion 508, the resistivity of the first electrode 504 can be loweredpractically. This can reduce nonuniformity of luminance that a portionaway from a current supply terminal is dark. When the size of theopening is sufficiently small, the presence of the auxiliary electrodecan be substantially disregarded when the lighting system is seen fromthe side of light emission, in other words, from the side of alight-transmitting substrate. Since the auxiliary electrode is notplaced in the direction of light emission, a material, a thickness, or aformation position of the auxiliary electrode can be arbitrarily set.Therefore, the auxiliary electrode can be formed selectively in aposition where voltage tends to drop, or can be entirely formed over thelight-emitting region of the lighting system.

Since the lighting system of the invention can reduce in-planenonuniformity of luminance which is caused by voltage drop due torelatively high resistivity of the first electrode, a lighting systemhaving favorable in-plane uniformity of luminance can be obtained.Specifically, the lighting system is preferably applied to a large-sizedlighting system.

Embodiment Mode 3

One mode of a lighting system according to the present invention isdescribed with reference to FIGS. 13A and 13B. Note that FIG. 13A is across-sectional view of the lighting system illustrated in a top view ofFIG. 13B taken along line A-A′.

In FIGS. 13A and 13B, an insulating layer 11 is formed over a substrate10. As shown in FIG. 13B, the insulating layer 11 is formed in a gridform over the substrate 10. In addition, the insulating layer 11contains a fluorescent substance. Then, a wiring 13 is formed over theinsulating layer 11.

A first electrode 12 is formed over the insulating layer 11 and thewiring 13 so that the insulating layer 11 and the wiring 13 are covered.Then, a layer containing a light-emitting substance 14 is formed overthe first electrode 12. Further, a second electrode 15 is formed overthe layer containing a light-emitting substance 14.

Here, the first electrode 12 is not limited particularly but preferableto be an electrode capable of transmitting visible light and the sameelectrode as the first electrode 102 described in Embodiment Mode 1 canbe used. In addition, the second electrode 15 is also not limitedparticularly and the same electrode as the second electrode 104described in Embodiment Mode 1 can be used. Further, the layercontaining a light-emitting substance 14 is not limited particularly andthe same layer as the layer containing a light-emitting substance 103described in Embodiment Mode 1 can be used.

The wiring 13 is not limited particularly but preferably formed of metalhaving a small resistance such as aluminum or copper.

In addition, the fluorescent substance included in the insulating layer11 is also not limited particularly and the following materials can beused: a polyaromatic compound such as 9,10-diphenylanthracene,9,10-di-2-naphthylanthracene, 9,10-bis(4-diphenylaminophenypanthracene,rubrene, 1,2,3,4,5-pentaphenylcyclopentadiene, p-sexiphenyl, perylene,or 2,5,8,11-tetra-tert-butylperylene; a heteroaromatic compound such as2,5-diphenyloxazole, 1,4-bis(5-phenyloxazole-2-yl)benzene,1,4-bis(4-methyl-5-phenyloxazole-2-yl)benzene,2-(1-naphtyl)-5-phenyloxazole, 2-(4-biphenylyl)-6-phenylbenzoxazole,2,5-bis(5-tert-buthylbenzoxazole-2-yl)thiophene,2-(4-biphenylyl)-6-phenylbenzoxazole,2-(4-biphenylyl)-5-phyenyl-1,3,4-oxadiazole,2-(4-tert-buthylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole,2,4-diphenyl-1,3,4-oxadiazole, or lophine; a coumarin-based compoundsuch as coumarin6, coumarin6H, coumarin7, coumarin 30, coumarin102,coumarin120, coumarin151, coumarin152, coumarin153, coumarin314,coumarin334, coumarin337, coumarin343, coumarin480D, or coumarin545T; apyran-based compound such as4-(dicyanomethylene)-2-methyl-6-[2-(4-dimethylaminophenyl)ethenyl]-4H-pyran,4-(dicyanomethylene)-2-methyl-6-[2-(julolidine-9-yl)ethenyl]-4H-pyran,4-(dicyanomethylene)-2-methyl-6-[2-(2,2,7,7-tetramethyljulolidine-9-yl)ethenyl]-4H-pyran,4-(dicyanomethylene)-2-tert-butyl-6-[2-(2,2,7,7-tetramethyljulolidine-9-yl)ethenyl]4H-pyran,or4-(dicyanomethylene)-2-isopropyl-6-[2-(2,2,7,7-tetramethyljulolidine-9-yl)ethenyl]-4H-pyran; a styrene-based compound such as1,1,4,4-tetraphenyl-1,3-butadiene, 1,4-bis(2-methylstyryl)benzene, or4,4′-bis(2,2-diphenylethenyl)biphenyl; or a xanthene-based compound suchas rhodamineB, rhodamine6G, rhodamine575, fluoresceine, or Nile Red.

Here, the surface height of the layer containing a light-emittingsubstance 14 (the height up to the surface of the layer containing alight-emitting substance 14 from a reference surface when a surface ofthe substrate 10, in other words, the substrate surface is regarded asthe reference surface) is preferably lower than the surface height ofthe insulating layer 11. Accordingly, luminescence in the layercontaining a light-emitting substance 14 enters the insulating layer 11much easily.

Further, an insulating layer including silicon nitride or silicon oxidemay be formed between the first electrode 12 and the substrate 10.Moisture which gets mixed by transmitting the substrate 10 can beprevented from penetrating the layer containing a light-emittingsubstance 14 by forming such an insulating layer.

A voltage drop in the first electrode 12 is decreased by providing thewiring 13 in the foregoing lighting system.

In addition, the lighting system having the foregoing structure emitslight when the light-emitting substance, which is excited by recombininga hole injected from the first electrode 12 and an electron injectedfrom the second electrode 15, returns to a ground state. Further, in thelighting system according to this embodiment mode, the luminescence withwaveguide in the direction parallel to the substrate surface enters theinsulating layer 11 and the fluorescent substance contained in theinsulating layer 11 emits light.

In this manner, luminescence is obtained from the entire substratesurface of the substrate 10 by light emission from the fluorescentsubstance contained in the insulating layer 11.

Embodiment Mode 4

This embodiment mode describes a method for manufacturing the lightingsystem described in Embodiment Mode 3 with reference to FIGS. 14A to 14Cand FIGS. 15A to 15C. Note that FIGS. 14A to 14C are cross-sectionalviews of the lighting system illustrated in top views of FIGS. 15A to15C taken along line A-A′, respectively.

First, after sequentially forming an insulating layer and a conductivelayer over a substrate 10, the insulating layer and the conductive layerare processed into desired shapes to form an insulating layer 11 and awiring 13. The insulating layer 11 is not limited particularly and aninsulating layer containing a fluorescent substance may be used.Siloxane, acrylic or polyimide, or the like can be given as an exampleof such an insulating layer. In addition, the wiring 13 is not limitedparticularly but preferably formed using a material with low resistivitysuch as aluminum or copper. Further, the aluminum may contain nickel,silicon, or the like.

Then, a first electrode 12 is formed over the substrate 10, theinsulating layer 11, and the wiring 13 so that the substrate 10, theinsulating layer 11, and the wiring 13 are covered. The first electrode12 is not limited particularly and preferably formed using the samematerial as the first electrode 102 described in Embodiment Mode 1. Inaddition, a method for manufacturing the first electrode 12 is notlimited particularly and may be formed by using a sputtering method orthe like.

In this embodiment mode, the insulating layer 11 and the wiring 13 areprocessed by being etched continuously using the same resist mask.However, not limiting thereto, after forming the insulating layer 11 ina desired shape, the wiring 13 may be formed by forming the conductivelayer that covers the insulating layer 11 and processing the conductivelayer into a desired shape, for example. In this embodiment mode, theinsulating layer 11 is formed in a grid form as illustrated in FIG. 15B.

Then, a layer containing a light-emitting substance 14 is formed so thatthe first electrode 12, the insulating layer 11, and the wiring 13 arecovered. The layer containing a light-emitting substance 14 is notlimited particularly and a layer having the same structure as the layercontaining a light-emitting substance 103 described in Embodiment Mode 1may be formed by using a vapor deposition method, an ink-jet method, orthe like.

Thereafter, a second electrode 15 is formed over the layer containing alight-emitting substance 14. The second electrode 15 is not limitedparticularly and preferably formed using the same material as the secondelectrode 104 described in Embodiment Mode 1. In addition, a method formanufacturing the second electrode 15 is also not limited particularlyand may be formed using a sputtering method, a vapor deposition method,or the like.

Further, it is preferable that the first electrode 12 and the secondelectrode 15 are stacked not to be in contact with each other. Forexample, the first electrode 12 and the second electrode 15 are formedso that one edge of both the electrodes is more inward than the layercontaining a light-emitting substance 14. Therefore, the first electrode12 and the second electrode 15 are prevented from being in contact witheach other.

Embodiment Mode 5

One mode of a lighting system of the present invention is described withreference to FIGS. 16A and 16B. Note that FIG. 16A is a cross-sectionalview of the lighting system illustrated in a top view of FIG. 16B takenalong line A-A′.

In FIGS. 16A and 16B, a first electrode 31 is formed over a substrate30. An insulating layer 32 having a depression is formed over the firstelectrode 31. As shown in FIG. 16B, the insulating layer 32 is formedover the first electrode 31 in a grid form. In addition, the insulatinglayer 32 contains a fluorescent substance. Then, a wiring 33 is formedinside the depression of the insulating layer 32. Further, an opening isformed inside the depression of the insulating layer 32 and the wiring33 is connected to the first electrode 31 through the opening.

The first electrode 31, the insulating layer 32, and the wiring 33 arecovered with a layer containing a light-emitting substance 34. Further,a second electrode 35 is formed over the layer containing alight-emitting substance 34.

Here, the wiring 33 is not limited particularly but preferably formed ofmetal having a small resistance such as aluminum or copper.

Further, the surface height of the layer containing a light-emittingsubstance 34 is preferably lower than the surface height of theinsulating layer 32.

In addition, the fluorescent substance is not limited particularly andthe fluorescent substance or the like as described in Embodiment Mode 3can be used.

The first electrode 31 is not limited particularly but preferable to bean electrode capable of transmitting visible light and the sameelectrode as the first electrode 102 described in Embodiment Mode 1 canbe used. In addition, the second electrode 35 is also not limitedparticularly and the same electrode as the second electrode 104described in Embodiment Mode 1 can be used. Further, the layercontaining a light-emitting substance 34 is not limited particularly andthe same layer as the layer containing a light-emitting substance 103described in Embodiment Mode 1 can be used.

A voltage drop in the first electrode 31 is decreased by providing thewiring 33 in the foregoing lighting system.

In addition, the lighting system having the foregoing structure emitslight when the light-emitting substance, which is excited by recombininga hole injected from the first electrode 31 and an electron injectedfrom the second electrode 35, returns to a ground state. Further, in thelighting system according to this embodiment mode, the luminescence withwaveguide in the direction parallel to the substrate surface enters theinsulating layer 32 and the fluorescent substance contained in theinsulating layer 32 emits light.

In this manner, luminescence is obtained from the entire substratesurface of the substrate 30 by light emission from the fluorescentsubstance contained in the insulating layer 32.

Embodiment 1

This embodiment describes a method for manufacturing the lighting systemaccording to the present invention illustrated in FIGS. 1A and 1B withreference to FIGS. 2A to 2D.

A transparent conductive film, which is a first electrode 202, is formedover a light-transmitting substrate 201. In this embodiment, a glasssubstrate is used as the light-transmitting substrate 201 and ITO isformed as the first electrode 202.

Then, a layer containing a light-emitting substance 203 is formed overthe first electrode 202. A known material can be used for the layercontaining a light-emitting substance 203. The layer containing alight-emitting substance may have a stacked structure of a plurality oflayers each containing a light-emitting substance.

A second electrode 204 is formed over the layer containing alight-emitting substance 203 (FIG. 2A). The second electrode 204 has anopening. After the second electrode is entirely formed over the layercontaining a light-emitting substance, the opening may be formed bypatterning the second electrode by a photolithography method or may beformed using a mask. In this embodiment, aluminum is used as the secondelectrode 204. After the second electrode 204 is entirely formed overthe layer containing a light-emitting substance 203, it is patterned bya photolithography method. Then, the opening is formed in the layercontaining a light-emitting substance, using the patterned secondelectrode as a mask (FIG. 2B).

An insulating film 205 is formed to cover the layer containing alight-emitting substance 203 and the second electrode 204 (FIG. 2C). Theinsulating film 205 also has an opening. After the insulating film isentirely formed, the opening may be formed by patterning the insulatingfilm by a photolithography method or may be formed using a mask. In thisembodiment, silicon oxide is used for the insulating film 205.

Thereafter, an auxiliary electrode 206 is formed (FIG. 2D). Theauxiliary electrode 206 is desirable to have low resistivity andaluminum is used in this embodiment. The auxiliary electrode 206 iselectrically connected to the first electrode 202 through an opening 207and insulated from the second electrode 204.

In this manner, ITO, which is the first electrode 202, is connected tothe auxiliary electrode 206 through the opening 207, and an effect ofvoltage drop due to relatively high resistivity of the first electrodecan be reduced. Therefore, in-plane inhomegeneity of luminance can bereduced when the lighting system is applied to a large-sized lightingsystem. In the case where the opening 207 is sufficiently small, thepresence of the auxiliary electrode can be substantially disregardedwhen the lighting system is seen from the side of light emission, inother words, from the side of the light transmitting substrate.

In this embodiment, although the layer containing a light-emittingsubstance is patterned using aluminum as a mask after being entirelyformed, the layer containing a light-emitting substance may be formedusing a mask to have an opening.

In addition, FIGS. 3A to 3C illustrate a method for forming each of alayer containing a light-emitting substance 303 and a second electrode304 using a mask. In other words, each of the layer containing alight-emitting substance 303 and a second electrode 304 is formed usinga mask after entirely forming a first electrode 302. An insulating film305, an auxiliary electrode 306, and an opening 307 may be formed in thesame manner as the foregoing method. At this time, the first electrodeis more certainly insulated from the second electrode by making theopening of the second electrode 304 larger than that of the layercontaining a light-emitting substance 303.

Embodiment 2

This embodiment describes a method for manufacturing the lighting systemaccording to the present invention illustrated in FIGS. 1A and 1B, whichdiffers from that of Embodiment 1, with reference to FIGS. 4A to 4C.

A transparent conductive film, which is a first electrode 402, is formedover a light-transmitting substrate 401. In this embodiment, a glasssubstrate is used as the light-transmitting substrate 401 and ITO isformed as the first electrode 402.

A layer containing a light-emitting substance 403 and a second electrode404 are sequentially formed (FIG. 4A). In this embodiment, aluminum isformed for the second electrode 404.

Thereafter, an opening is formed by delivering a laser beam to thelight-transmitting substrate 401 side (FIG. 4B). A laser beam having awavelength enough to be transmitted through the glass substrate and ITOand absorbed by the layer containing a light-emitting substance 403 andthe second electrode 404, is used as the laser beam. In this embodiment,a laser beam having a 532 nm wavelength is used. The laser beam having a532 nm wavelength can be obtained by converting a fundamental wave (1064nm wavelength) of a YAG laser, a YVO₄ laser, or the like into the secondharmonic by a nonlinear optical element. After absorbing the laser beam,the layer containing a light-emitting substance and the second electrodeare heated and sublimated, thereby forming the opening. After formingthe opening, an insulating film 405 and an auxiliary electrode 406 areformed in the same manner as Embodiment 1 so that the first electrode402 is electrically connected to the auxiliary electrode 406 through anopening 407 (FIG. 4C).

Embodiment 3

This embodiment describes a method for manufacturing the lighting systemaccording to the present invention illustrated in FIGS. 5A and 5B withreference to FIGS. 6A to 6C and FIGS. 7A and 7B.

A second electrode 602, a layer containing light-emitting substance 603,and a first electrode 604 are formed over a thin substrate 601 formed ofa flexible material. In this embodiment, aluminum is formed as thesecond electrode 602 and ITO is formed as the first electrode 604 over apolyester film (FIG. 6A).

Then, the substrate 601, the second electrode 602, the layer containinga light-emitting substance 603, and the first electrode 604 are providedwith an opening (FIG. 6B). Since the substrate 601 is formed of aflexible material, the opening can be easily formed by applying physicalstrength.

A silicon oxide film is formed as an insulating film 605. The siliconoxide film is formed using a mask by a sputtering method or a vapordeposition method (FIG. 6C). The silicon oxide film is formed to wraparound to the opposite surface of an intended surface through theopening by using a sputtering method or a vapor deposition method.According to this, the second electrode 602 is more certainly insulatedfrom an auxiliary electrode 606.

Then, the auxiliary electrode 606 is formed. First, silver is formed onthe first electrode 604 side by a printing method. At this time, anopening 607 is filled with silver by using a printing method (FIG. 7A).Next, the silver is entirely formed on the substrate 601 side (FIG. 7B).Accordingly, the first electrode 604 is electrically connected to theauxiliary electrode 606. Thus, an effect of voltage drop due torelatively high resistivity of the first electrode can be reduced.Therefore, a lighting system having favorable in-plane uniformity ofluminance can be obtained when the lighting system is applied to alarge-sized lighting system.

In the structure of this embodiment, ITO, which is the first electrode,is connected to silver, which is the auxiliary electrode in thedirection of light emission. However, in the case where the opening 607is sufficiently small, the presence of the auxiliary electrode can besubstantially disregarded when the lighting system is seen from the sideof light emission, in other words, from the side of the first electrode.

Embodiment 4

This embodiment describes an example of an overall structure of thelighting system according to the present invention with reference toFIGS. 8A and 8B.

FIGS. 8A and 8B are a top view and cross-sectional view of the lightingsystem of the invention, respectively. The lighting system of theinvention includes a substrate 801, a first electrode 802, a layercontaining a light-emitting substance 803, a second electrode 804, aninsulating film 805, and an auxiliary electrode 806. The first electrode802 is electrically connected to the auxiliary electrode 806 through anopening 807. A light-emitting region is provided with a plurality ofopenings 807. In addition, a second insulating film 808 is formed at theend of the luminescence region, which prevents the first electrode 802and the second electrode 804 from shorting. Current supply terminals 809are each connected to the second electrode 804 and the auxiliaryelectrode 806. Then, the light-emitting region is sealed with a sealant810. The sealant is desirable to be a material which transmits as littlemoisture and oxygen as possible to prevent deterioration of the layercontaining a light-emitting substance. In addition, the insidesurrounded by the sealant is filled with a filler 811. An inert gas(nitrogen, argon, or the like) may be filled instead of the filler inthe inside surrounded by the sealant. The same material as the sealantmay be filled.

Although FIGS. 8A and 8B each exemplify the structure described inEmbodiment 1, the structure described in Embodiment 2 and Embodiment 3can also be employed as a lighting system by sealing in the same manner.

Embodiment 5

This embodiment describes an example of a device using the lightingsystem according to the present invention with reference to FIG. 9 andFIGS. 10A to 10C.

FIG. 9 is an example of a liquid crystal display device using thelighting system of the invention as a backlight. The liquid crystaldisplay device illustrated in FIG. 9 includes a casing 901, a liquidcrystal layer 902, a backlight 903, and a casing 904. The liquid crystallayer 902 is connected to a driver IC 905. In addition, the lightingsystem of the invention is used as the backlight 903 and current issupplied through a terminal 906.

A backlight having favorable in-plane uniformity of luminance can beobtained by using the lighting system of the invention as a backlight ofa liquid crystal display device; therefore, the quality of the liquidcrystal display device is enhanced. Since the backlight can have largearea, the liquid crystal display device can also have large area.Further, the light-emitting element is thin and consumes less power;therefore, the liquid crystal display device can also be thinned andmade to consume less power.

FIG. 10A is an example of using the lighting system of the invention asindoor lighting. The lighting system of the invention is asurface-emitting lighting system and has favorable in-plane uniformityof luminance even when it has large area. Therefore, an entire ceiling,for example, can be provided with the lighting system of the invention.Not only the ceiling but also a wall, a floor, a column, or the like canbe provided with the lighting system of the invention. Further, sincethe lighting system of the invention is flexible, the lighting systemcan be provided on a curved surface. Furthermore, the lighting systemcan be used not only indoors but also outdoors and can be provided on abuilding wall or the like as outdoor light.

FIG. 10B is an example of using the lighting system of the invention aslighting in a tunnel. Since the lighting system of the invention isflexible, the lighting system can be formed along a curved inner wall ofa tunnel.

FIG. 10C is an example of using the lighting system of the invention asinterior lighting. Since the lighting system of the invention is thinand flexible and is a surface-emitting type, it can be processed into adesired shape as illustrated in FIG. 10B.

In addition, the lighting system of the invention can also be used forlighting in taking a picture. When the picture is taken, a picturesimilar to the one taken with a subject illuminated by natural light canbe taken when a subject is illuminated by large-sized light with uniformluminance.

The present application is based on Japanese Patent Application serialNo. 2004-166041 filed on Jun. 3, 2004 with the Japanese Patent Office,the entire contents of which are hereby incorporated by reference.

What is claimed is:
 1. A lighting system comprising: a first electrode;a layer including a light-emitting substance over the first electrode; asecond electrode over the layer the light-emitting substance; a wiringbetween the first electrode and the layer including the light-emittingsubstance; and an insulating layer in contact with a side surface of thefirst electrode, the insulating layer being located between the firstelectrode and the second electrode, wherein the wiring is in contactwith a top surface of the first electrode, wherein the first electrodecontinuously extends so as to overlap with a plurality of openings ofthe wiring, and wherein the second electrode continuously extends so asto overlap with the plurality of openings of the wiring.
 2. The lightingsystem according to claim 1, wherein the insulating layer is located ina periphery of the lighting system.
 3. The lighting system according toclaim 1, wherein the wiring has a grid form.
 4. The lighting systemaccording to claim 1, wherein the first electrode includes indium tinoxide, and wherein the wiring includes aluminum.
 5. The lighting systemaccording to claim 1, further comprising: a second insulating layerbetween the first electrode and the layer including the light-emittingsubstance.
 6. The lighting system according to claim 5, wherein thesecond insulating layer has a depression having an opening, and thewiring is connected to the first electrode through the opening of thedepression.
 7. The lighting system according to claim 1, wherein thelighting system is one selected from the group consisting of abacklight, an indoor lighting, an outdoor light, a lighting in a tunnel,and an interior lighting.
 8. The lighting system according to claim 1,wherein the lighting system emits white light.
 9. A lighting systemcomprising: a substrate; a first electrode over the substrate, the firstelectrode including a transparent conductive layer; a layer including alight-emitting substance over the first electrode; a second electrodeover the layer the light-emitting substance; a wiring between the firstelectrode and the layer including the light-emitting substance; and aninsulating layer in contact with a side surface of the first electrode,the insulating layer being located between the first electrode and thesecond electrode, wherein the wiring is in contact with a top surface ofthe first electrode, wherein the first electrode continuously extends soas to overlap with a plurality of openings of the wiring, and whereinthe second electrode continuously extends so as to overlap with theplurality of openings of the wiring.
 10. The lighting system accordingto claim 9, wherein the insulating layer is located in a periphery ofthe lighting system.
 11. The lighting system according to claim 9,wherein the wiring has a grid form.
 12. The lighting system according toclaim 9, wherein the first electrode includes indium tin oxide, andwherein the wiring includes aluminum.
 13. The lighting system accordingto claim 9, further comprising: a second insulating layer between thefirst electrode and the layer including the light-emitting substance.14. The lighting system according to claim 13, wherein the secondinsulating layer has a depression having an opening, and the wiring isconnected to the first electrode through the opening of the depression.15. The lighting system according to claim 9, wherein the lightingsystem is one selected from the group consisting of a backlight, anindoor lighting, an outdoor light, a lighting in a tunnel, and aninterior lighting.
 16. The lighting system according to claim 9, whereinthe lighting system emits white light.
 17. A lighting system comprising:a substrate; a first electrode over the substrate, the first electrodeincluding a transparent conductive layer; a layer including alight-emitting substance over the first electrode; a second electrodeover the layer the light-emitting substance; a wiring between the firstelectrode and the layer including the light-emitting substance; aninsulating layer in contact with a side surface of the first electrode,the insulating layer being located between the first electrode and thesecond electrode; and a sealant over a top surface the second electrode,wherein the sealant faces to a side surface of the second electrode,wherein the wiring is in contact with a top surface of the firstelectrode, wherein the first electrode continuously extends so as tooverlap with a plurality of openings of the wiring, and wherein thesecond electrode continuously extends so as to overlap with theplurality of openings of the wiring.
 18. The lighting system accordingto claim 17, wherein the insulating layer is located in a periphery ofthe lighting system.
 19. The lighting system according to claim 17,wherein the wiring has a grid form.
 20. The lighting system according toclaim 17, wherein the first electrode includes indium tin oxide, andwherein the wiring includes aluminum.
 21. The lighting system accordingto claim 17, further comprising: a second insulating layer between thefirst electrode and the layer including the light-emitting substance.22. The lighting system according to claim 21, wherein the secondinsulating layer has a depression having an opening, and the wiring isconnected to the first electrode through the opening of the depression.23. The lighting system according to claim 17, wherein the lightingsystem is one selected from the group consisting of a backlight, anindoor lighting, an outdoor light, a lighting in a tunnel, and aninterior lighting.
 24. The lighting system according to claim 17,wherein the lighting system emits white light.